Driver core: change mem class_devices to be real devices
[linux-2.6.git] / drivers / char / mem.c
1 /*
2  *  linux/drivers/char/mem.c
3  *
4  *  Copyright (C) 1991, 1992  Linus Torvalds
5  *
6  *  Added devfs support. 
7  *    Jan-11-1998, C. Scott Ananian <cananian@alumni.princeton.edu>
8  *  Shared /dev/zero mmaping support, Feb 2000, Kanoj Sarcar <kanoj@sgi.com>
9  */
10
11 #include <linux/mm.h>
12 #include <linux/miscdevice.h>
13 #include <linux/slab.h>
14 #include <linux/vmalloc.h>
15 #include <linux/mman.h>
16 #include <linux/random.h>
17 #include <linux/init.h>
18 #include <linux/raw.h>
19 #include <linux/tty.h>
20 #include <linux/capability.h>
21 #include <linux/smp_lock.h>
22 #include <linux/ptrace.h>
23 #include <linux/device.h>
24 #include <linux/highmem.h>
25 #include <linux/crash_dump.h>
26 #include <linux/backing-dev.h>
27 #include <linux/bootmem.h>
28 #include <linux/pipe_fs_i.h>
29 #include <linux/pfn.h>
30
31 #include <asm/uaccess.h>
32 #include <asm/io.h>
33
34 #ifdef CONFIG_IA64
35 # include <linux/efi.h>
36 #endif
37
38 /*
39  * Architectures vary in how they handle caching for addresses
40  * outside of main memory.
41  *
42  */
43 static inline int uncached_access(struct file *file, unsigned long addr)
44 {
45 #if defined(__i386__)
46         /*
47          * On the PPro and successors, the MTRRs are used to set
48          * memory types for physical addresses outside main memory,
49          * so blindly setting PCD or PWT on those pages is wrong.
50          * For Pentiums and earlier, the surround logic should disable
51          * caching for the high addresses through the KEN pin, but
52          * we maintain the tradition of paranoia in this code.
53          */
54         if (file->f_flags & O_SYNC)
55                 return 1;
56         return !( test_bit(X86_FEATURE_MTRR, boot_cpu_data.x86_capability) ||
57                   test_bit(X86_FEATURE_K6_MTRR, boot_cpu_data.x86_capability) ||
58                   test_bit(X86_FEATURE_CYRIX_ARR, boot_cpu_data.x86_capability) ||
59                   test_bit(X86_FEATURE_CENTAUR_MCR, boot_cpu_data.x86_capability) )
60           && addr >= __pa(high_memory);
61 #elif defined(__x86_64__)
62         /* 
63          * This is broken because it can generate memory type aliases,
64          * which can cause cache corruptions
65          * But it is only available for root and we have to be bug-to-bug
66          * compatible with i386.
67          */
68         if (file->f_flags & O_SYNC)
69                 return 1;
70         /* same behaviour as i386. PAT always set to cached and MTRRs control the
71            caching behaviour. 
72            Hopefully a full PAT implementation will fix that soon. */      
73         return 0;
74 #elif defined(CONFIG_IA64)
75         /*
76          * On ia64, we ignore O_SYNC because we cannot tolerate memory attribute aliases.
77          */
78         return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
79 #else
80         /*
81          * Accessing memory above the top the kernel knows about or through a file pointer
82          * that was marked O_SYNC will be done non-cached.
83          */
84         if (file->f_flags & O_SYNC)
85                 return 1;
86         return addr >= __pa(high_memory);
87 #endif
88 }
89
90 #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
91 static inline int valid_phys_addr_range(unsigned long addr, size_t count)
92 {
93         if (addr + count > __pa(high_memory))
94                 return 0;
95
96         return 1;
97 }
98
99 static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
100 {
101         return 1;
102 }
103 #endif
104
105 /*
106  * This funcion reads the *physical* memory. The f_pos points directly to the 
107  * memory location. 
108  */
109 static ssize_t read_mem(struct file * file, char __user * buf,
110                         size_t count, loff_t *ppos)
111 {
112         unsigned long p = *ppos;
113         ssize_t read, sz;
114         char *ptr;
115
116         if (!valid_phys_addr_range(p, count))
117                 return -EFAULT;
118         read = 0;
119 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
120         /* we don't have page 0 mapped on sparc and m68k.. */
121         if (p < PAGE_SIZE) {
122                 sz = PAGE_SIZE - p;
123                 if (sz > count) 
124                         sz = count; 
125                 if (sz > 0) {
126                         if (clear_user(buf, sz))
127                                 return -EFAULT;
128                         buf += sz; 
129                         p += sz; 
130                         count -= sz; 
131                         read += sz; 
132                 }
133         }
134 #endif
135
136         while (count > 0) {
137                 /*
138                  * Handle first page in case it's not aligned
139                  */
140                 if (-p & (PAGE_SIZE - 1))
141                         sz = -p & (PAGE_SIZE - 1);
142                 else
143                         sz = PAGE_SIZE;
144
145                 sz = min_t(unsigned long, sz, count);
146
147                 /*
148                  * On ia64 if a page has been mapped somewhere as
149                  * uncached, then it must also be accessed uncached
150                  * by the kernel or data corruption may occur
151                  */
152                 ptr = xlate_dev_mem_ptr(p);
153
154                 if (copy_to_user(buf, ptr, sz))
155                         return -EFAULT;
156                 buf += sz;
157                 p += sz;
158                 count -= sz;
159                 read += sz;
160         }
161
162         *ppos += read;
163         return read;
164 }
165
166 static ssize_t write_mem(struct file * file, const char __user * buf, 
167                          size_t count, loff_t *ppos)
168 {
169         unsigned long p = *ppos;
170         ssize_t written, sz;
171         unsigned long copied;
172         void *ptr;
173
174         if (!valid_phys_addr_range(p, count))
175                 return -EFAULT;
176
177         written = 0;
178
179 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
180         /* we don't have page 0 mapped on sparc and m68k.. */
181         if (p < PAGE_SIZE) {
182                 unsigned long sz = PAGE_SIZE - p;
183                 if (sz > count)
184                         sz = count;
185                 /* Hmm. Do something? */
186                 buf += sz;
187                 p += sz;
188                 count -= sz;
189                 written += sz;
190         }
191 #endif
192
193         while (count > 0) {
194                 /*
195                  * Handle first page in case it's not aligned
196                  */
197                 if (-p & (PAGE_SIZE - 1))
198                         sz = -p & (PAGE_SIZE - 1);
199                 else
200                         sz = PAGE_SIZE;
201
202                 sz = min_t(unsigned long, sz, count);
203
204                 /*
205                  * On ia64 if a page has been mapped somewhere as
206                  * uncached, then it must also be accessed uncached
207                  * by the kernel or data corruption may occur
208                  */
209                 ptr = xlate_dev_mem_ptr(p);
210
211                 copied = copy_from_user(ptr, buf, sz);
212                 if (copied) {
213                         written += sz - copied;
214                         if (written)
215                                 break;
216                         return -EFAULT;
217                 }
218                 buf += sz;
219                 p += sz;
220                 count -= sz;
221                 written += sz;
222         }
223
224         *ppos += written;
225         return written;
226 }
227
228 #ifndef __HAVE_PHYS_MEM_ACCESS_PROT
229 static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
230                                      unsigned long size, pgprot_t vma_prot)
231 {
232 #ifdef pgprot_noncached
233         unsigned long offset = pfn << PAGE_SHIFT;
234
235         if (uncached_access(file, offset))
236                 return pgprot_noncached(vma_prot);
237 #endif
238         return vma_prot;
239 }
240 #endif
241
242 #ifndef CONFIG_MMU
243 static unsigned long get_unmapped_area_mem(struct file *file,
244                                            unsigned long addr,
245                                            unsigned long len,
246                                            unsigned long pgoff,
247                                            unsigned long flags)
248 {
249         if (!valid_mmap_phys_addr_range(pgoff, len))
250                 return (unsigned long) -EINVAL;
251         return pgoff;
252 }
253
254 /* can't do an in-place private mapping if there's no MMU */
255 static inline int private_mapping_ok(struct vm_area_struct *vma)
256 {
257         return vma->vm_flags & VM_MAYSHARE;
258 }
259 #else
260 #define get_unmapped_area_mem   NULL
261
262 static inline int private_mapping_ok(struct vm_area_struct *vma)
263 {
264         return 1;
265 }
266 #endif
267
268 static int mmap_mem(struct file * file, struct vm_area_struct * vma)
269 {
270         size_t size = vma->vm_end - vma->vm_start;
271
272         if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size))
273                 return -EINVAL;
274
275         if (!private_mapping_ok(vma))
276                 return -ENOSYS;
277
278         vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
279                                                  size,
280                                                  vma->vm_page_prot);
281
282         /* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */
283         if (remap_pfn_range(vma,
284                             vma->vm_start,
285                             vma->vm_pgoff,
286                             size,
287                             vma->vm_page_prot))
288                 return -EAGAIN;
289         return 0;
290 }
291
292 static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
293 {
294         unsigned long pfn;
295
296         /* Turn a pfn offset into an absolute pfn */
297         pfn = PFN_DOWN(virt_to_phys((void *)PAGE_OFFSET)) + vma->vm_pgoff;
298
299         /*
300          * RED-PEN: on some architectures there is more mapped memory
301          * than available in mem_map which pfn_valid checks
302          * for. Perhaps should add a new macro here.
303          *
304          * RED-PEN: vmalloc is not supported right now.
305          */
306         if (!pfn_valid(pfn))
307                 return -EIO;
308
309         vma->vm_pgoff = pfn;
310         return mmap_mem(file, vma);
311 }
312
313 #ifdef CONFIG_CRASH_DUMP
314 /*
315  * Read memory corresponding to the old kernel.
316  */
317 static ssize_t read_oldmem(struct file *file, char __user *buf,
318                                 size_t count, loff_t *ppos)
319 {
320         unsigned long pfn, offset;
321         size_t read = 0, csize;
322         int rc = 0;
323
324         while (count) {
325                 pfn = *ppos / PAGE_SIZE;
326                 if (pfn > saved_max_pfn)
327                         return read;
328
329                 offset = (unsigned long)(*ppos % PAGE_SIZE);
330                 if (count > PAGE_SIZE - offset)
331                         csize = PAGE_SIZE - offset;
332                 else
333                         csize = count;
334
335                 rc = copy_oldmem_page(pfn, buf, csize, offset, 1);
336                 if (rc < 0)
337                         return rc;
338                 buf += csize;
339                 *ppos += csize;
340                 read += csize;
341                 count -= csize;
342         }
343         return read;
344 }
345 #endif
346
347 extern long vread(char *buf, char *addr, unsigned long count);
348 extern long vwrite(char *buf, char *addr, unsigned long count);
349
350 /*
351  * This function reads the *virtual* memory as seen by the kernel.
352  */
353 static ssize_t read_kmem(struct file *file, char __user *buf, 
354                          size_t count, loff_t *ppos)
355 {
356         unsigned long p = *ppos;
357         ssize_t low_count, read, sz;
358         char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
359
360         read = 0;
361         if (p < (unsigned long) high_memory) {
362                 low_count = count;
363                 if (count > (unsigned long) high_memory - p)
364                         low_count = (unsigned long) high_memory - p;
365
366 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
367                 /* we don't have page 0 mapped on sparc and m68k.. */
368                 if (p < PAGE_SIZE && low_count > 0) {
369                         size_t tmp = PAGE_SIZE - p;
370                         if (tmp > low_count) tmp = low_count;
371                         if (clear_user(buf, tmp))
372                                 return -EFAULT;
373                         buf += tmp;
374                         p += tmp;
375                         read += tmp;
376                         low_count -= tmp;
377                         count -= tmp;
378                 }
379 #endif
380                 while (low_count > 0) {
381                         /*
382                          * Handle first page in case it's not aligned
383                          */
384                         if (-p & (PAGE_SIZE - 1))
385                                 sz = -p & (PAGE_SIZE - 1);
386                         else
387                                 sz = PAGE_SIZE;
388
389                         sz = min_t(unsigned long, sz, low_count);
390
391                         /*
392                          * On ia64 if a page has been mapped somewhere as
393                          * uncached, then it must also be accessed uncached
394                          * by the kernel or data corruption may occur
395                          */
396                         kbuf = xlate_dev_kmem_ptr((char *)p);
397
398                         if (copy_to_user(buf, kbuf, sz))
399                                 return -EFAULT;
400                         buf += sz;
401                         p += sz;
402                         read += sz;
403                         low_count -= sz;
404                         count -= sz;
405                 }
406         }
407
408         if (count > 0) {
409                 kbuf = (char *)__get_free_page(GFP_KERNEL);
410                 if (!kbuf)
411                         return -ENOMEM;
412                 while (count > 0) {
413                         int len = count;
414
415                         if (len > PAGE_SIZE)
416                                 len = PAGE_SIZE;
417                         len = vread(kbuf, (char *)p, len);
418                         if (!len)
419                                 break;
420                         if (copy_to_user(buf, kbuf, len)) {
421                                 free_page((unsigned long)kbuf);
422                                 return -EFAULT;
423                         }
424                         count -= len;
425                         buf += len;
426                         read += len;
427                         p += len;
428                 }
429                 free_page((unsigned long)kbuf);
430         }
431         *ppos = p;
432         return read;
433 }
434
435
436 static inline ssize_t
437 do_write_kmem(void *p, unsigned long realp, const char __user * buf,
438               size_t count, loff_t *ppos)
439 {
440         ssize_t written, sz;
441         unsigned long copied;
442
443         written = 0;
444 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
445         /* we don't have page 0 mapped on sparc and m68k.. */
446         if (realp < PAGE_SIZE) {
447                 unsigned long sz = PAGE_SIZE - realp;
448                 if (sz > count)
449                         sz = count;
450                 /* Hmm. Do something? */
451                 buf += sz;
452                 p += sz;
453                 realp += sz;
454                 count -= sz;
455                 written += sz;
456         }
457 #endif
458
459         while (count > 0) {
460                 char *ptr;
461                 /*
462                  * Handle first page in case it's not aligned
463                  */
464                 if (-realp & (PAGE_SIZE - 1))
465                         sz = -realp & (PAGE_SIZE - 1);
466                 else
467                         sz = PAGE_SIZE;
468
469                 sz = min_t(unsigned long, sz, count);
470
471                 /*
472                  * On ia64 if a page has been mapped somewhere as
473                  * uncached, then it must also be accessed uncached
474                  * by the kernel or data corruption may occur
475                  */
476                 ptr = xlate_dev_kmem_ptr(p);
477
478                 copied = copy_from_user(ptr, buf, sz);
479                 if (copied) {
480                         written += sz - copied;
481                         if (written)
482                                 break;
483                         return -EFAULT;
484                 }
485                 buf += sz;
486                 p += sz;
487                 realp += sz;
488                 count -= sz;
489                 written += sz;
490         }
491
492         *ppos += written;
493         return written;
494 }
495
496
497 /*
498  * This function writes to the *virtual* memory as seen by the kernel.
499  */
500 static ssize_t write_kmem(struct file * file, const char __user * buf, 
501                           size_t count, loff_t *ppos)
502 {
503         unsigned long p = *ppos;
504         ssize_t wrote = 0;
505         ssize_t virtr = 0;
506         ssize_t written;
507         char * kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
508
509         if (p < (unsigned long) high_memory) {
510
511                 wrote = count;
512                 if (count > (unsigned long) high_memory - p)
513                         wrote = (unsigned long) high_memory - p;
514
515                 written = do_write_kmem((void*)p, p, buf, wrote, ppos);
516                 if (written != wrote)
517                         return written;
518                 wrote = written;
519                 p += wrote;
520                 buf += wrote;
521                 count -= wrote;
522         }
523
524         if (count > 0) {
525                 kbuf = (char *)__get_free_page(GFP_KERNEL);
526                 if (!kbuf)
527                         return wrote ? wrote : -ENOMEM;
528                 while (count > 0) {
529                         int len = count;
530
531                         if (len > PAGE_SIZE)
532                                 len = PAGE_SIZE;
533                         if (len) {
534                                 written = copy_from_user(kbuf, buf, len);
535                                 if (written) {
536                                         if (wrote + virtr)
537                                                 break;
538                                         free_page((unsigned long)kbuf);
539                                         return -EFAULT;
540                                 }
541                         }
542                         len = vwrite(kbuf, (char *)p, len);
543                         count -= len;
544                         buf += len;
545                         virtr += len;
546                         p += len;
547                 }
548                 free_page((unsigned long)kbuf);
549         }
550
551         *ppos = p;
552         return virtr + wrote;
553 }
554
555 #if (defined(CONFIG_ISA) || defined(CONFIG_PCI)) && !defined(__mc68000__)
556 static ssize_t read_port(struct file * file, char __user * buf,
557                          size_t count, loff_t *ppos)
558 {
559         unsigned long i = *ppos;
560         char __user *tmp = buf;
561
562         if (!access_ok(VERIFY_WRITE, buf, count))
563                 return -EFAULT; 
564         while (count-- > 0 && i < 65536) {
565                 if (__put_user(inb(i),tmp) < 0) 
566                         return -EFAULT;  
567                 i++;
568                 tmp++;
569         }
570         *ppos = i;
571         return tmp-buf;
572 }
573
574 static ssize_t write_port(struct file * file, const char __user * buf,
575                           size_t count, loff_t *ppos)
576 {
577         unsigned long i = *ppos;
578         const char __user * tmp = buf;
579
580         if (!access_ok(VERIFY_READ,buf,count))
581                 return -EFAULT;
582         while (count-- > 0 && i < 65536) {
583                 char c;
584                 if (__get_user(c, tmp)) {
585                         if (tmp > buf)
586                                 break;
587                         return -EFAULT; 
588                 }
589                 outb(c,i);
590                 i++;
591                 tmp++;
592         }
593         *ppos = i;
594         return tmp-buf;
595 }
596 #endif
597
598 static ssize_t read_null(struct file * file, char __user * buf,
599                          size_t count, loff_t *ppos)
600 {
601         return 0;
602 }
603
604 static ssize_t write_null(struct file * file, const char __user * buf,
605                           size_t count, loff_t *ppos)
606 {
607         return count;
608 }
609
610 static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf,
611                         struct splice_desc *sd)
612 {
613         return sd->len;
614 }
615
616 static ssize_t splice_write_null(struct pipe_inode_info *pipe,struct file *out,
617                                  loff_t *ppos, size_t len, unsigned int flags)
618 {
619         return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
620 }
621
622 #ifdef CONFIG_MMU
623 /*
624  * For fun, we are using the MMU for this.
625  */
626 static inline size_t read_zero_pagealigned(char __user * buf, size_t size)
627 {
628         struct mm_struct *mm;
629         struct vm_area_struct * vma;
630         unsigned long addr=(unsigned long)buf;
631
632         mm = current->mm;
633         /* Oops, this was forgotten before. -ben */
634         down_read(&mm->mmap_sem);
635
636         /* For private mappings, just map in zero pages. */
637         for (vma = find_vma(mm, addr); vma; vma = vma->vm_next) {
638                 unsigned long count;
639
640                 if (vma->vm_start > addr || (vma->vm_flags & VM_WRITE) == 0)
641                         goto out_up;
642                 if (vma->vm_flags & (VM_SHARED | VM_HUGETLB))
643                         break;
644                 count = vma->vm_end - addr;
645                 if (count > size)
646                         count = size;
647
648                 zap_page_range(vma, addr, count, NULL);
649                 zeromap_page_range(vma, addr, count, PAGE_COPY);
650
651                 size -= count;
652                 buf += count;
653                 addr += count;
654                 if (size == 0)
655                         goto out_up;
656         }
657
658         up_read(&mm->mmap_sem);
659         
660         /* The shared case is hard. Let's do the conventional zeroing. */ 
661         do {
662                 unsigned long unwritten = clear_user(buf, PAGE_SIZE);
663                 if (unwritten)
664                         return size + unwritten - PAGE_SIZE;
665                 cond_resched();
666                 buf += PAGE_SIZE;
667                 size -= PAGE_SIZE;
668         } while (size);
669
670         return size;
671 out_up:
672         up_read(&mm->mmap_sem);
673         return size;
674 }
675
676 static ssize_t read_zero(struct file * file, char __user * buf, 
677                          size_t count, loff_t *ppos)
678 {
679         unsigned long left, unwritten, written = 0;
680
681         if (!count)
682                 return 0;
683
684         if (!access_ok(VERIFY_WRITE, buf, count))
685                 return -EFAULT;
686
687         left = count;
688
689         /* do we want to be clever? Arbitrary cut-off */
690         if (count >= PAGE_SIZE*4) {
691                 unsigned long partial;
692
693                 /* How much left of the page? */
694                 partial = (PAGE_SIZE-1) & -(unsigned long) buf;
695                 unwritten = clear_user(buf, partial);
696                 written = partial - unwritten;
697                 if (unwritten)
698                         goto out;
699                 left -= partial;
700                 buf += partial;
701                 unwritten = read_zero_pagealigned(buf, left & PAGE_MASK);
702                 written += (left & PAGE_MASK) - unwritten;
703                 if (unwritten)
704                         goto out;
705                 buf += left & PAGE_MASK;
706                 left &= ~PAGE_MASK;
707         }
708         unwritten = clear_user(buf, left);
709         written += left - unwritten;
710 out:
711         return written ? written : -EFAULT;
712 }
713
714 static int mmap_zero(struct file * file, struct vm_area_struct * vma)
715 {
716         if (vma->vm_flags & VM_SHARED)
717                 return shmem_zero_setup(vma);
718         if (zeromap_page_range(vma, vma->vm_start, vma->vm_end - vma->vm_start, vma->vm_page_prot))
719                 return -EAGAIN;
720         return 0;
721 }
722 #else /* CONFIG_MMU */
723 static ssize_t read_zero(struct file * file, char * buf, 
724                          size_t count, loff_t *ppos)
725 {
726         size_t todo = count;
727
728         while (todo) {
729                 size_t chunk = todo;
730
731                 if (chunk > 4096)
732                         chunk = 4096;   /* Just for latency reasons */
733                 if (clear_user(buf, chunk))
734                         return -EFAULT;
735                 buf += chunk;
736                 todo -= chunk;
737                 cond_resched();
738         }
739         return count;
740 }
741
742 static int mmap_zero(struct file * file, struct vm_area_struct * vma)
743 {
744         return -ENOSYS;
745 }
746 #endif /* CONFIG_MMU */
747
748 static ssize_t write_full(struct file * file, const char __user * buf,
749                           size_t count, loff_t *ppos)
750 {
751         return -ENOSPC;
752 }
753
754 /*
755  * Special lseek() function for /dev/null and /dev/zero.  Most notably, you
756  * can fopen() both devices with "a" now.  This was previously impossible.
757  * -- SRB.
758  */
759
760 static loff_t null_lseek(struct file * file, loff_t offset, int orig)
761 {
762         return file->f_pos = 0;
763 }
764
765 /*
766  * The memory devices use the full 32/64 bits of the offset, and so we cannot
767  * check against negative addresses: they are ok. The return value is weird,
768  * though, in that case (0).
769  *
770  * also note that seeking relative to the "end of file" isn't supported:
771  * it has no meaning, so it returns -EINVAL.
772  */
773 static loff_t memory_lseek(struct file * file, loff_t offset, int orig)
774 {
775         loff_t ret;
776
777         mutex_lock(&file->f_dentry->d_inode->i_mutex);
778         switch (orig) {
779                 case 0:
780                         file->f_pos = offset;
781                         ret = file->f_pos;
782                         force_successful_syscall_return();
783                         break;
784                 case 1:
785                         file->f_pos += offset;
786                         ret = file->f_pos;
787                         force_successful_syscall_return();
788                         break;
789                 default:
790                         ret = -EINVAL;
791         }
792         mutex_unlock(&file->f_dentry->d_inode->i_mutex);
793         return ret;
794 }
795
796 static int open_port(struct inode * inode, struct file * filp)
797 {
798         return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
799 }
800
801 #define zero_lseek      null_lseek
802 #define full_lseek      null_lseek
803 #define write_zero      write_null
804 #define read_full       read_zero
805 #define open_mem        open_port
806 #define open_kmem       open_mem
807 #define open_oldmem     open_mem
808
809 static const struct file_operations mem_fops = {
810         .llseek         = memory_lseek,
811         .read           = read_mem,
812         .write          = write_mem,
813         .mmap           = mmap_mem,
814         .open           = open_mem,
815         .get_unmapped_area = get_unmapped_area_mem,
816 };
817
818 static const struct file_operations kmem_fops = {
819         .llseek         = memory_lseek,
820         .read           = read_kmem,
821         .write          = write_kmem,
822         .mmap           = mmap_kmem,
823         .open           = open_kmem,
824         .get_unmapped_area = get_unmapped_area_mem,
825 };
826
827 static const struct file_operations null_fops = {
828         .llseek         = null_lseek,
829         .read           = read_null,
830         .write          = write_null,
831         .splice_write   = splice_write_null,
832 };
833
834 #if (defined(CONFIG_ISA) || defined(CONFIG_PCI)) && !defined(__mc68000__)
835 static const struct file_operations port_fops = {
836         .llseek         = memory_lseek,
837         .read           = read_port,
838         .write          = write_port,
839         .open           = open_port,
840 };
841 #endif
842
843 static const struct file_operations zero_fops = {
844         .llseek         = zero_lseek,
845         .read           = read_zero,
846         .write          = write_zero,
847         .mmap           = mmap_zero,
848 };
849
850 /*
851  * capabilities for /dev/zero
852  * - permits private mappings, "copies" are taken of the source of zeros
853  */
854 static struct backing_dev_info zero_bdi = {
855         .capabilities   = BDI_CAP_MAP_COPY,
856 };
857
858 static const struct file_operations full_fops = {
859         .llseek         = full_lseek,
860         .read           = read_full,
861         .write          = write_full,
862 };
863
864 #ifdef CONFIG_CRASH_DUMP
865 static const struct file_operations oldmem_fops = {
866         .read   = read_oldmem,
867         .open   = open_oldmem,
868 };
869 #endif
870
871 static ssize_t kmsg_write(struct file * file, const char __user * buf,
872                           size_t count, loff_t *ppos)
873 {
874         char *tmp;
875         ssize_t ret;
876
877         tmp = kmalloc(count + 1, GFP_KERNEL);
878         if (tmp == NULL)
879                 return -ENOMEM;
880         ret = -EFAULT;
881         if (!copy_from_user(tmp, buf, count)) {
882                 tmp[count] = 0;
883                 ret = printk("%s", tmp);
884                 if (ret > count)
885                         /* printk can add a prefix */
886                         ret = count;
887         }
888         kfree(tmp);
889         return ret;
890 }
891
892 static const struct file_operations kmsg_fops = {
893         .write =        kmsg_write,
894 };
895
896 static int memory_open(struct inode * inode, struct file * filp)
897 {
898         switch (iminor(inode)) {
899                 case 1:
900                         filp->f_op = &mem_fops;
901                         filp->f_mapping->backing_dev_info =
902                                 &directly_mappable_cdev_bdi;
903                         break;
904                 case 2:
905                         filp->f_op = &kmem_fops;
906                         filp->f_mapping->backing_dev_info =
907                                 &directly_mappable_cdev_bdi;
908                         break;
909                 case 3:
910                         filp->f_op = &null_fops;
911                         break;
912 #if (defined(CONFIG_ISA) || defined(CONFIG_PCI)) && !defined(__mc68000__)
913                 case 4:
914                         filp->f_op = &port_fops;
915                         break;
916 #endif
917                 case 5:
918                         filp->f_mapping->backing_dev_info = &zero_bdi;
919                         filp->f_op = &zero_fops;
920                         break;
921                 case 7:
922                         filp->f_op = &full_fops;
923                         break;
924                 case 8:
925                         filp->f_op = &random_fops;
926                         break;
927                 case 9:
928                         filp->f_op = &urandom_fops;
929                         break;
930                 case 11:
931                         filp->f_op = &kmsg_fops;
932                         break;
933 #ifdef CONFIG_CRASH_DUMP
934                 case 12:
935                         filp->f_op = &oldmem_fops;
936                         break;
937 #endif
938                 default:
939                         return -ENXIO;
940         }
941         if (filp->f_op && filp->f_op->open)
942                 return filp->f_op->open(inode,filp);
943         return 0;
944 }
945
946 static const struct file_operations memory_fops = {
947         .open           = memory_open,  /* just a selector for the real open */
948 };
949
950 static const struct {
951         unsigned int            minor;
952         char                    *name;
953         umode_t                 mode;
954         const struct file_operations    *fops;
955 } devlist[] = { /* list of minor devices */
956         {1, "mem",     S_IRUSR | S_IWUSR | S_IRGRP, &mem_fops},
957         {2, "kmem",    S_IRUSR | S_IWUSR | S_IRGRP, &kmem_fops},
958         {3, "null",    S_IRUGO | S_IWUGO,           &null_fops},
959 #if (defined(CONFIG_ISA) || defined(CONFIG_PCI)) && !defined(__mc68000__)
960         {4, "port",    S_IRUSR | S_IWUSR | S_IRGRP, &port_fops},
961 #endif
962         {5, "zero",    S_IRUGO | S_IWUGO,           &zero_fops},
963         {7, "full",    S_IRUGO | S_IWUGO,           &full_fops},
964         {8, "random",  S_IRUGO | S_IWUSR,           &random_fops},
965         {9, "urandom", S_IRUGO | S_IWUSR,           &urandom_fops},
966         {11,"kmsg",    S_IRUGO | S_IWUSR,           &kmsg_fops},
967 #ifdef CONFIG_CRASH_DUMP
968         {12,"oldmem",    S_IRUSR | S_IWUSR | S_IRGRP, &oldmem_fops},
969 #endif
970 };
971
972 static struct class *mem_class;
973
974 static int __init chr_dev_init(void)
975 {
976         int i;
977
978         if (register_chrdev(MEM_MAJOR,"mem",&memory_fops))
979                 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
980
981         mem_class = class_create(THIS_MODULE, "mem");
982         for (i = 0; i < ARRAY_SIZE(devlist); i++)
983                 device_create(mem_class, NULL,
984                               MKDEV(MEM_MAJOR, devlist[i].minor),
985                               devlist[i].name);
986
987         return 0;
988 }
989
990 fs_initcall(chr_dev_init);